The ability to provide oxygen to skin tissue is critical for many medical conditions including diaper rash, decubitus ulcers, diabetic ulcers, burns, and wounds. Insufficient oxygenation of compromised tissue will result in slow healing, infections, scar development, and in the worst cases, tissue death and amputation.
The effect of oxygen tension on wound healing has been extensively studied. (For a review, see Whitney, J. D. (1989)). Wound healing is dependent upon several processes including proliferation of fibroblasts, collagen synthesis, angiogenesis and re-epithelialization. Animal studies have shown that several of these processes are affected by the subcutaneous partial pressure of oxygen (pO.sub.2). For example, supplemental oxygen can lead to increased rate of collagen deposition, epithelialization and improved healing of split thickness grafts. Increased subcutaneous pO.sub.2 has also been shown to improve bacterial defenses.
Various methods of administration of oxygen gas, either through inhalation of the gas, or by topical treatment with the gas have been disclosed, including administering oxygen gas to a patient in a hyperbaric chamber.
Dermatitis develops when the skin is subjected to conditions that breakdown the corneum stratum. The stratum corneum is the outer layer of skin and is composed in adults of about 25 to 30 layers of keratinocytes. The main purpose of this part of the skin is to reduce water loss, repel microbial infection, protect deeper layers, and provide a water-repellant layer. Damage to this layer can occur, for example, when an infant's skin is exposed for long periods to urine and feces, these waste products lower the skin pH and result in the breakdown of the stratum corneum, which is thinner in infants compared to adults. Although moisture alone will loosen this layer and allow for friction irritation to occur, urine breakdown by fecal enzymes can reduce, or acidify, the skin resulting in chemical irritation. Decubitus ulcers can occur when patients must spend long periods in bed, and the resulting pressure points on the skin cause irritation lesions, commonly called bedsores. Some studies have shown that 8-40% of intensive care patients suffer from decubitus ulcers. According to a 2004 study, the incidence rate for decubitus ulcers calculated 474,692 new cases per year, with 34,320 deaths resulting therefrom. Another study calculated that 8% of spinal cord patients died as a result of decubitus ulcers and their complications.
The wound healing process, depending on the type of injury to the skin, is an intricate process that involves the steps of inflammation, proliferation, and remodelling. During inflammation, bacteria and debris are phagocytized and removed, and factors are released that cause the migration and division of cells involved in the proliferative phase.
The proliferative phase is characterized by angiogenesis, deposition of collagen, formation of granular tissue, re-epithelialization, and wound contraction. In angiogenesis, new blood vessels are formed by vascular endothelial cells. In fibroplasia and formation of granular tissue, fibroblasts grow and form a new, provisional extracellular matrix (ECM) by excreting collagen and fibronectin.
Simultaneously, re-epithelialization occurs, providing a new epithelial layer. It is at this stage that oxygenation of the skin is critical to wound healing.
In the remodeling phase, collagen is remodeled and realigned along tension lines and cells that are no longer needed are removed by apoptosis.
Common treatments include use of zinc oxide pastes, powders, petroleum-based creams, and even mild steroid creams to reduce excess moisture, provide antibacterial activity or barriers, and to reduce damage caused by the body's own inflammatory processes. Similar treatments are used in hospital settings to treat adult patient decubitus ulcers.
While some treatments have focused on an antibacterial approach or an approach of keeping skin dry, other have focused on pH. For example, U.S. Pat. No. 6,805,875, to Bartels, discloses topical compositions and treatments of a skin condition commonly known as “diaper rash” and more particularly, acidic-type diaper rash and other skin irritations caused by acidic bodily secretions, usually resulting from teething, antibiotic dosages, bacterial infections, and an acidic diet.
U.S. Pat. No. 6,423,323 to Neuborg, discloses a foam skin cream made by mixing a two-phase mixture of fatty acids and moisturizers with a propellant, the foam is adjusted to pH 7.6 to 8.2.
Oxygenation was disclosed in U.S. Reissue 37,274 to Gardner discloses a multi-step skin treatment to reduce aging effects that includes, in sequence, exfoliation, cleansing, hydration, and oxygenation. Exfoliation is by treating with alkaline, then acidic solutions, cleansing and hydrating is by applying various solutions, and oxygenation is disclosed as being accomplished using a tank of oxygen and a misting device.
U.S. Pat. No. 5,336,209 to Porzilli discloses a multilayer dressing which allows for increased ventilation. The removal of the top dressing is stated to increase the rate of oxygenation, improving the rate of epidermal healing.
U.S. Pat. No. 6,649,145 to McGrath, discloses methods and compositions for increasing oxygen levels by adminstering superoxygenated compositions, e.g. compositions that contain microbubbles of oxygen to increase the level to 55-220 ppm oxygen in a low temperature composition.
Accordingly, there is still a need for methods and compositions for treating skin injuries that increase the oxygen delivery to the skin in a convenient and efficient manner.